A pumping artificial lung.

Abstract

The authors have developed a single device that performs the functions of a centrifugal pump and a membrane artificial lung. Unlike other systems that combine pre-existing components, our device is constructed so that the vanes of an impeller pump are made up of gas exchanging microporous fibers. The device has a variety of applications: in an easily primed emergency cardiopulmonary bypass circuit, as a low surface area component of extracorporeal life support (ECLS) circuits, and as a low volume, high perfusion rate bridge to transplant. Five prototype devices, with gas exchange surface areas ranging from 0.09 to 0.35 m2, have been tested in vitro to characterize the gas exchange and pumping capabilities of the device. These small devices pump fluid effectively. The larger device could pump 2.7 l/min with 91 mmHg pressure difference from inlet to outlet. These preliminary devices transferred to only 33 ml/min of oxygen (O2) and 35 ml/min of carbon dioxide (CO2), however. The combination of pumping ability and gas exchange is encouraging, but it is apparent that larger surface areas and less blood shunting around the gas exchanging impellers are needed for sufficient gas exchange. Somewhat higher surface areas are feasible within the pump-head casing used for these preliminary prototypes; larger casings could be used for still higher surface areas.